Insulated assemblies presently known in the art incorporate the use of various polymeric substances in combination with other materials. One such assembly includes a butylated polymer in which there is embedded an undulating metal spacer. Although useful, this type of sealant strip is limited in that the metal spacer, over time, becomes exposed to the substrates which results in a drastic depreciation in the efficiency of the strip. The particular difficulty arises with moisture vapour transmission when the spacer becomes exposed and contacts the substrates.
Further, many of the butylated polymers currently used in insulated glass assemblies are impregnated with a desiccant. This results in a further problem, namely decreased adhesiveness of the butylated sealant.
Glover et al. in U.S. Pat. No. 4,950,344, provide a spacer assembly including a foam body separated by a vapour barrier and further including a sealant means about the periphery of the assembly. Although this arrangement is particularly efficient from an energy point of view, one of the key limitations is that the assembly must be fabricated in a number of steps. Generally speaking, the sealant must be gunned about the periphery in a subsequent step to the initial placement of the spacer. This has ramifications during the manufacturing phase and is directly related to increased production costs and, therefore, increased costs in the assembly itself.
One of the primary weaknesses in existing spacer bodies and spacer assemblies relates to the transmission of energy through the spacer. Typically, in existing arrangements the path of heat energy flow through the spacer is simplified as opposed to torturous and in the case of the former, the result is easy transmission of energy from one substrate to the other via the spacer. In the prior art, this difficulty is compounded by the fact that materials are employed which have a strong propensity to conduct thermal energy.
It has been found particularly advantageous to incorporate high thermal performance materials. In one embodiment, a major component of the spacer may comprise a soft or reasonably soft, resilient insulated body, of a material having low thermal conductivity. Such materials may be cellular and examples of materials found to be useful include natural and synthetic elastomers (rubber), cork, EPDM, silicones, polyurethanes and foamed polysilicones, urethanes and other suitable foamed materials. Significant benefits arise from the choice of these materials since not only are they excellent insulators from an energy point of view but additionally, depending on the materials used, the entire spacer can maintain a certain degree of resiliency. This is important where windows, for example, engaged with such a strip experience fluctuating pressure forces as well as a thermal contraction and expansion. By making use of a resilient body, these stresses are alleviated and accordingly, the stress is not transferred to the substrates as would be the case, for example, in assemblies incorporating rigid spacers.
Where the insulating body is composed of a foam material, the foam body may be manufactured from thermoplastic or thermosetting plastics. Suitable examples of the thermosets include silicone and polyurethane. In terms of the thermoplastics, examples include silicone foam or elastomers, one example of the latter being, SANTOPRENE.TM.. Advantages ascribable to the aforementioned compounds include, in addition to what has been included above, high durability, minimal outgassing, low compression, high resiliency and temperature stability, inter alia.
Of particular use are the silicone and the polyurethane foams. These types of materials offer high strength and provide significant structural integrity to the assembly. The foam material is particularly convenient for use in insulating glazing or glass assemblies since a high volume of air can be incorporated into the material without sacrificing any structural integrity of the body. This is convenient since air is known to be a good insulator and when the use of foam is combined with a material having a low thermal conductivity together with the additional features of the spacer to be set forth hereinafter, a highly efficient composite spacer results. In addition, foam is not susceptible to contraction or expansion in situations where temperature fluctuations occur. This clearly is beneficial for maintaining a long-term uncompromised seal in an insulated substrate assembly. The insulating body may be selected from a host of suitable materials as set forth herein and in addition, it will be understood that suitable materials having naturally occurring interstices or materials synthetically created having the interstices would provide utility.
One of the operating difficulties associated with the employment of foams and other cellular material is directed to the fact that the transverse dimension of the spacer body increases when the body is bent or flexed to a corner in an insulated assembly. Typically, the body bulges outwardly exteriorly of the interior atmosphere of the assembly, while the interior is compressed and the substrate engaging surfaces bulge transversely to increase the overall transverse dimension of the body. This reduces the uniformity in the transverse dimension at a flex point and therefore "compresses" or "squeezes" sealant material at the substrate engaging surface to the different thicknesses across the substrate engaging surface. This is of concern with respect to stress on substrates and the efficiency of the seal.
It would be desirable to have a composite spacer which overcomes the limitations of the previously employed materials and the prior art and the energy limitations associated therewith. The present invention is directed to satisfying the limitations.